. It deals
with sound pressure and gain, mean values and maximum values.An input sound pressure of 60 dB serves as the reference for the test setting, the Reference Test Setting (RTS). To determine the reference, the gain control is set so that the average of the output sound pressure level (OSPL), the OSPL90 value, is -77 dB at high frequencies. At 500 Hz and 800 Hz, the input sound pressure level is 77 dB, and at 1.6 kHz, it is 65 dB. The OSPL90 value is the output sound pressure level (OSPL) for an input sound pressure of 90 dB.